The present invention relates to a device for positioning components within endoscopic systems, having a hermetically sealed housing, an outer ring element mounted to rotate about the outer side of said housing and carrying on its circumference at least one outer magnet, another inner ring element mounted inside said housing and carrying at least one inner magnet, said magnets being arranged such that any rotation of said outer ring element has the effect to move said at least one inner magnet by magnetic coupling, such movement serving the purpose to position the respective components.
A device of this kind has been known from DE 195 21 654 A1.
The term positioning as used in the context of the present invention includes axial displacement and/or circumferential displacement to bring the components into a desired position.
The term components includes, for example, optical components such as lenses in an optical head of an endoscope. An axial displacement of the system serves for focusing or adjusting the optical system. The term components also includes mechanical components, which are to be swung into and out of an optical system, such as filters, diaphragms or the like. The positioning device may be handled from the proximal end of the endoscopic system, while the component to be moved may be arranged also at the distal end and may be connected with the positioning device via some linkage.
The term endoscopic systems as used in the present invention is meant to describe endoscopes and also endoscopic camera systems.
The term hermetically sealed housing as used in the present invention is meant to describe a housing sufficiently tight to allow it to be autoclaved, for example, without any risk of humidity or liquids, i.e. contaminations, penetrating into the interior of the housing as a result of the extreme temperature variations encountered. The outer magnets of the outer ring element arranged around the outer side of the tight housing interact in the way of a magnetic coupling with the inner magnets of the inner ring element arranged inside the tight housing.
In the case of the known optical device mentioned at the outset the inner magnet is received in a helically shaped slot of a sleeve mounted stationarily inside the tight housing. A lens mount, carrying the lenses of a lens group, is mounted for axial displacement and rotation inside the sleeve. The inner magnet, being configured as a circular magnet, engages a radial blind bore provided on the outer circumference of the lens mount.
The magnet of the outer rotatable ring element is configured as a rectangular magnet that interacts with the circular magnet, i.e. is arranged substantially opposite the latter.
Rotation of the outer ring element together with the rectangular magnet causes the inner circular magnet to be rotated simultaneously. Since the circular element is received in a helically shaped slot in the sleeve, it also moves in axial direction.
Consequently, the rectangular magnet located on the outer ring must have an axial extension that corresponds to the maximum axial displacement of the inner circular magnet as it moves along the helically shaped slot in the sleeve.
The fact that the circular magnet engages a radial blind bore on the outer side of the lens mount results in the latter being axially displaced in response to the axial advance motion of the circular magnet.
This configuration is connected with the disadvantage that due to the axial mobility of the inner magnet the outer ring magnet must have a very long axial extension, i.e. a big overall size, which leads to bulky and large structures. The magnet in the outer ring being relatively big, it emits magnetic stray fields to the outside which may interfere with systems that work with electron beams, such as monitors or endoscopic cameras, or the like. In addition, the inner circular magnet is mechanically connected with two different components, namely the outer stationary sleeve with the helically shaped slot, and the blind bore in the inner mount of the optical system. In order to ensure sure jam-free operation, it is necessary to use precisely manufactured parts and also to provide a certain play with the result that especially reversing movements will lead to jerky movements with changes in adjustment of the optical system.
U.S. Pat. No. 5,359,992 describes a device for positioning components within endoscopic systems, where two diametrically opposite helically shaped slots are provided in the outer ring element in which diametrically opposite circular magnets are inserted. The circular magnets engage an axial directed recess in the outer side of a sleeve arranged in the ring. Rotation of the outer ring thus causes the outer magnet to move in axial direction. Inside the closed section, there are provided corresponding diametrically opposite magnets which follow the movements of the outer magnet, thereby effecting the coupling action. The inner set element, with the inner magnets, is not guided mechanically so that in the event the inner element should get out of the magnetic field of the outer magnet, due to a shock or some other impact, it can be moved toward and backward, and can be rotated inside the housing. In order to reestablish the proper function, the endoscope then has to be pivoted until the interaction between the outer and inner magnets has been reestablished.
A similar structure has been known from DE 88 10 044 U1, where a magnet arranged on the inner side of the outer ring interacts with an inner magnet of very long extension.
The outer magnet is moved in axial direction thereby entraining the inner magnet and effecting the coupling effect.
A telescope functioning according to that basic lens-adjusting principle has been known from German Patent Specification No. 970 298. Here again, there is a risk that mechanical shocks may bring the inner magnet out of magnetic interaction with the outer magnet.
It is therefore an object of the present invention to improve a device of the afore-mentioned kind in such a way that effective positioning of components and safe functioning can be permanently ensured with a structure of small overall size.
This object is achieved according to the invention, with regard to the device for positioning components within endoscopic systems of the type cited initially, by the fact that both, said outer and said inner ring element, are configured as rotatable, but axially nondisplaceable rings carrying oppositely arranged said magnets, and that said inner ring is mechanically connected with said components to be positioned.
The invention now deviates from the principle that at least one magnet, or even both, are movable in axial direction.
The system now only comprises rotatable rings that carry the magnets so that the axial extension of the magnetic coupling is relatively short. This on the one hand results in a relatively short overall length of the magnetic coupling, and avoids in addition large axial areas through which interfering magnetic fields might be emitted, so that any interfering radiation can be screened effectively, i.e. without extensive structures.
The relative position between the inner and the outer magnets does not change during rotation. When the outer ring is rotated together with the outer magnet, the inner ring with the inner magnet rotates correspondingly. Accordingly, the system does absolutely without any helically shaped guides for moving the magnets. Translation of the rotary movement of the inner ring is effected by the mechanical connection between the components to be positioned and the ring.
All in all, the mechanical coupling has a very short overall axial extension, and does with only two fundamental components, namely an outer ring with the at least one outer magnet and an inner ring with the at least one inner magnet, so that the constituent parts are little susceptible to faults and provide permanent functional safety. Due to the fact that the rings are axially fixed against displacement, mechanical shocks or impact cannot interrupt the magnetic coupling in the axial direction. The narrow overall size in axial direction permits magnetic screening to be realized by simple structural measures. And in the radial direction, the magnetic coupling also exhibits a moderate overall size, since the two rings, being arranged substantially in one plane, constitute components of relatively small size.
According to a further embodiment of the invention, the outer ring is provided on its outer side with a ferromagnetic screening in order to screen any interfering, outwardly directed magnetic stray fields.
This feature provides the advantage that the outer screening ensures that no interfering, outwardly directed stray fields will emanate from the magnetic coupling.
According to another embodiment of the invention, the outer ring is made from a ferromagnetic material with the at least one magnet mounted on its inner side.
This feature provides the advantage that the screening constitutes at the same time the carrier element and/or the ring on whose inner side the at least one magnet is mounted.
This also leads to structurally pimple parts of small overall size.
According to a further embodiment of the invention, a plurality of radially polarized magnets are mounted on the inner side of the outer ring, in circumferentially distributed arrangement.
By arranging a plurality of radially polarized magnets it is possible to give the ring an extremely narrow design in axial direction as the plurality of the magnets permit the necessary coupling with the inner magnet to be achieved in any rotary position.
According to a further embodiment of the invention, the outer ring is configured as a set collar.
This feature provides the advantage that the outer ring acts simultaneously as set collar, i.e. that the latter can be gripped from the outer side, which means that an especially small number of components is required, which in turn leads to a narrow structure also in radial direction.
According to a further embodiment of the invention, the outer ring is connected on its outer side with a set collar.
This feature provides the advantage that the materials of the outer ring and of the set collar surrounding the latter can be freely selected so that special demands placed on the design can be met in case, for example, it should be desired to adapt the outer design of the set collar to the outer design of the remaining endoscopic system. There is further the possibility to have the set collar simultaneously perform the function of the screening, and to make the inner ring for example from a plastic material with the magnets embedded therein. The outer ring can be rotated manually, or can be driven via a motor, especially an electric motor.
According to a further embodiment of the invention, a plurality of radially polarized magnets are provided on the outer side of the inner ring in circumferentially distributed arrangement.
This feature provides the considerable advantage, especially in combination with the previously mentioned feature relating to the plurality of magnets provided on the inner side of the outer ring, that a coupling effect sufficient to move even relatively heavy or heavy-moving components can be ensured with rings of extremely narrow axial overall size. This further contributes to a relatively small structure, i.e. a narrow structure in both the axial and the radial direction.
According to a further embodiment of the invention, the number, circumferential distribution and axial extension of the magnets are equal for the inner and the outer ring.
This feature provides the considerable advantage that an intense magnetic flux occurs between the individual identical oppositely arranged magnets so that no relative displacements between the outer and the inner ring will occur even if the outer ring should be moved abruptly or insensitively. This contributes significantly toward increasing the operating safety.
According to another embodiment of the invention, the inner ring is connected, via a thread, with a component arranged for axial displacement in the housing so that any rotary movement of the inner ring will be translated into an axial movement of the component.
This feature provides the advantage that the rotary movement of the inner ring can be translated by simple mechanical means to an axial movement of the component.
According to a further embodiment of the invention, the axially movable component is protected against rotary movement.
This feature provides the advantage, especially in the case of optical systems, that the latter will be moved only in axial direction, without being rotated, which in the case of complex optical systems, especially in the case of non-spherical lenses, could result in optical displacements.
According to a further embodiment of the invention, the axially displaceable component is subjected to the force of a spring in the axial direction.
This feature provides the advantage that the play of the mechanical translation of the rotary movement to an axial movement, necessarily existing, is permitted to occur, by the force of the spring, only in a very defined end position of the play, and that the reversal of the axial displacement is likewise effected in a jerk-free and smooth elastic fashion.
According to a further embodiment of the invention, the inner ring carries components that can be swung into and out of an optical system by rotation of the inner ring.
This feature provides the considerable advantage that components such as filters, screens, diaphragms, or the like, can be laterally swung into and out of an optical system by means of the magnetic coupling. The rotary axis of the rings does not coincide with the optical axis in this case. The components are swung into and out of the optical system in the way of a revolver magazine.
According to a further embodiment of the invention, the range of rotation of the outer ring is limited.
This feature, which is known as such, provides the advantage that any excessive rotation is rendered impossible.
According to a further embodiment of the invention, the magnets are designed as Smxe2x80x94Co magnets, comprising preferably an alloy of SmCo5 and/or Sm2Co17 based on ferrous metal.
This feature provides the advantage that such Samarium-Cobalt magnets are highly temperature-resistant up to 200xc2x0 Celsius. The extreme temperature variations to which endoscopic systems are exposed during autoclaving do not impair the magnetization.
It is understood that the features mentioned above and those yet to be explained below can be used not only in the respective combinations indicated, but also in other combinations or in isolation, without leaving the context of the present invention.
The invention will be described in more detail and explained below with reference to certain selected exemplifying embodiments. In the drawings: